View the Size of the Sparse File of a Database Snapshot (Transact-SQL)

This topic describes how to use Transact-SQL to verify that a SQL Server database file is a sparse file and to find out its actual and maximum sizes. Sparse files, which are a feature of the NTFS file system, are used by SQL Server database snapshots.

Note

During database snapshot creation, sparse files are created by using the file names in the CREATE DATABASE statement. These file names are stored in sys.master_files in the physical_name column. In sys.database_files (whether in the source database or in a snapshot), the physical_name column always contains the names of the source database files.

The maximum size to which a sparse can grow is the size of the corresponding source database file at the time of the snapshot creation. To learn this size, you can use one of the following alternatives:

Using Windows Command Prompt:

Use Windows dir commands.

Select the sparse file, open the file Properties dialog box in Windows, and look at the Size value.

On the instance of SQL Server:

Select the size column from either sys.database_files in the database snapshot or from sys.master_files. The value of size column reflects the maximum space, in SQL pages, that the snapshot can ever use; this value is equivalent to the Windows Size field, except that it is represented in terms of the number of SQL pages in the file; the size in bytes is: